Chinese scientists who were barred from a Nasa conference next month on the grounds of national security may now be allowed to attend after the head of the US space agency admitted it had been a mistake to refuse their applications.

Charlie Bolden, Nasa's chief administrator, has ordered a review of the Chinese scientists' applications in the hope of re-inviting any who pass security checks for foreign nationals once the government shutdown has been resolved. He blamed the debacle on middle managers who acted without proper authority.

But it is unclear whether the move to undo the damage will work. The necessary security checks can take several weeks and it is not clear when the relevant government offices will reopen for business. The conference is due to start on 4 November and will draw scientists from around the world to discuss the latest results from Nasa's now defunct Kepler planet-hunting mission.

Space scientists in the US became aware of the ban only when Chinese researchers working in US labs had their applications to attend the conference turned down. There were calls to boycott the meeting, and several prominent researchers withdrew in protest.

Geoff Marcy, a pioneer in exoplanets at the University of California, Berkeley, said he would reverse his boycott if Chinese nationals had a chance to attend.

The Chinese researchers were notified of the rejection in an email sent from Nasa's Ames facility in California, where the conference is due to be held. The message quoted section 535(b) of public law 113-6, and went on to say that the "federal legislation passed last March forbids us from hosting any citizens of the People's Republic of China at a conference held at facilities of the National Aeronautics and Space Administration. Regarding those who are already working at other institutions, due to security issues resulting from recent congressional actions, they are under the same constraints."

Prompted by the Guardian's story on the furore, congressman Frank Wolf, chair of the House appropriations subcommittee that has jurisdiction over Nasa, contacted the Nasa chief administrator to correct the agency's interpretation of the law.

"It places no restrictions on activities involving individual Chinese nationals unless those nationals are acting as official representatives of the Chinese government. As such, the email from Nasa Ames mischaracterises the law and is inaccurate," Wolf wrote.

The congressman went on to suggest that Nasa Ames staff had confused the law with a temporary moratorium that Bolden had brought in amid concerns over what Wolf called "serious security protocol flaws" at Ames and Nasa's Langley research centre. To clarify, Wolf said: "Any restriction against Chinese nationals on Nasa centres is entirely an agency policy and not covered under the statutory restriction."

Wolf's letter to Bolden stressed the danger posed to the US by Chinese espionage and raised much deeper concerns over the running of Nasa's Ames facility. "The misrepresentation of Nasa policy quoted in the Guardian article is the latest in a series of questionable actions taken by the Ames Centre leadership that have resulted in criminal investigations of export violations and inspector general reviews of illegitimate contracts issued by the centre. I believe the centre has become a rat's nest of inappropriate and possibly illegal activities that appear to have occurred with the concurrence of the centre's leadership," the congressman wrote.

In a reply to Wolf on Thursday, Bolden said it was "unfortunate" that Chinese nationals had been refused attendance to the Kepler conference and blamed the mistake on middle managers at the Nasa Ames site.

"Mid-level managers at Ames, in performing the due diligence they believed appropriate following a period of significant concern and scrutiny from Congress about our foreign access to Nasa facilities, meetings and websites, acted without consulting Nasa HQ," Bolden wrote. A more formal response to the congressman's six-page letter will be drawn up once the government is reopened.

Nasa's intention to re-invite the Chinese scientists was welcomed on Friday, and researchers hope to get the conference back on track at the Nasa centre. Steven Kawaler, a co-organiser of the conference, said: "I am delighted by this development. I do expect most of our international colleagues who were excluded from the meeting will now be able to attend, and will be informed about their updated status very soon."